/Engine/Source/Runtime/SlateCore/Public/FastUpdate/WidgetProxy.h
Similar toSWidget::Paintbut use the saved PersistenState. Only paint/tick if needed.
the new and previous LayerId is the widget was painted.
[FUpdateResult](API\Runtime\SlateCore\FastUpdate\FWidgetProxy\FUpdateResult) Update ( const [FPaintArgs](API\Runtime\SlateCore\Types\FPaintArgs) & PaintArgs, [FSlateWindowElementList](API\Runtime\SlateCore\Rendering\FSlateWindowElementList) & OutDrawElements )